The invention relates to a sensor or security device that has a releasable connection. This releasable connection can be in the form of a plug connection such as a telephone jack connection. The sensor can work with central security systems or other sensors described in U.S. Pat. Nos. 6,300,874; 6,285,283; 6,278,365; 6,215,400; 6,147,603; 6,104,289; 6,050,616; 5,821,857; 5,796,337; 5,561,417; 5,543,782 all assigned to Protex International Corp. and all incorporated herein by reference.